Systems and methods for making and using electrical stimulation systems with improved rf compatibility

ABSTRACT

A method of forming a control module for an electrical stimulation system, the control module including an electronic subassembly disposed in an inner space of a casing and a feedthrough housing disposed along a portion of the casing, includes: forming an RF-diverting assembly having capacitive elements electrically-coupled to a feedthrough ground; electrically-coupling the capacitive elements to conductive pathways extending along a non-conductive substrate; electrically-coupling the conductive pathways to feedthrough pins extending through the feedthrough housing from a location external to the casing to a location within the inner space of the casing; electrically-coupling the conductive pathways to the electronic subassembly such that the conductive pathways electrically-couple the feedthrough pins to the electronic subassembly; electrically-coupling the feedthrough ground to an electrically-conductive portion of the feedthrough housing; and electrically-coupling the electrically-conductive portion of the feedthrough housing to an electrically-conductive portion of an outer surface of the casing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/862,205 filed Apr. 12, 2013 which claims the benefit under 35 U.S.C.§119(e) of U.S. Provisional Patent Application Ser. No. 61/624,938 filedon Apr. 16, 2012, both of which are incorporated herein by reference.

FIELD

The present invention is directed to the area of implantable electricalstimulation systems and methods of making and using the systems. Thepresent invention is also directed to implantable electrical stimulationcontrol modules that modulate undesired propagation of current intoelectronic systems within the control modules, as well as methods ofmaking and using the control modules and electrical stimulation systems.

BACKGROUND

Implantable electrical stimulation systems have proven therapeutic in avariety of diseases and disorders. For example, spinal cord stimulationsystems have been used as a therapeutic modality for the treatment ofchronic pain syndromes. Peripheral nerve stimulation has been used totreat incontinence, as well as a number of other applications underinvestigation. Functional electrical stimulation systems have beenapplied to restore some functionality to paralyzed extremities in spinalcord injury patients.

Stimulators have been developed to provide therapy for a variety oftreatments. A stimulator can include a control module (with a pulsegenerator), one or more leads, and an array of stimulator electrodes oneach lead. The stimulator electrodes are in contact with or near thenerves, muscles, or other tissue to be stimulated. The pulse generatorin the control module generates electrical pulses that are delivered bythe electrodes to body tissue.

Conventional implanted electrical stimulation systems are oftenincompatible with magnetic resonance imaging (“MRI”) due to the largeradio frequency (“RF”) pulses used during MRI. The RF pulses cangenerate transient signals in the conductors and electrodes of animplanted lead. These signals can have deleterious effects including,for example, unwanted heating of the tissue causing tissue damage,induced currents in the lead, or premature failure of electroniccomponents.

BRIEF SUMMARY

In one embodiment, a method of forming a control module for anelectrical stimulation system, the control module including anelectronic subassembly disposed in an inner space of a casing and afeedthrough housing disposed along a portion of the casing, includes:forming an RF-diverting assembly, the RF-diverting assembly comprising aplurality of capacitive elements electrically coupled to a feedthroughground; electrically coupling the plurality of capacitive elements to aplurality of conductive pathways extending along a non-conductivesubstrate; electrically coupling the plurality of conductive pathways toa plurality of feedthrough pins extending through the feedthroughhousing from a location external to the casing to a location within theinner space of the casing; electrically coupling the plurality ofconductive pathways to the electronic subassembly such that theplurality of conductive pathways electrically couple the plurality offeedthrough pins to the electronic subassembly; electrically couplingthe feedthrough ground to at least one electrically-conductive portionof the feedthrough housing; and electrically coupling the at least oneelectrically-conductive portion of the feedthrough housing to at leastone electrically-conductive portion of an outer surface of the casing.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present invention aredescribed with reference to the following drawings. In the drawings,like reference numerals refer to like parts throughout the variousfigures unless otherwise specified.

For a better understanding of the present invention, reference will bemade to the following Detailed Description, which is to be read inassociation with the accompanying drawings, wherein:

FIG. 1 is a schematic view of one embodiment of an electricalstimulation system that includes a paddle body coupled to a controlmodule via lead bodies, according to the invention;

FIG. 2 is a schematic view of another embodiment of an electricalstimulation system that includes a percutaneous lead body coupled to acontrol module via a lead body, according to the invention;

FIG. 3A is a schematic view of one embodiment of a plurality ofconnector assemblies disposed in the control module of FIG. 1, theconnector assemblies configured and arranged to receive the proximalportions of the lead bodies of FIG. 1, according to the invention;

FIG. 3B is a schematic view of one embodiment of a connector assemblydisposed in the control module of FIG. 2, the connector assemblyconfigured and arranged to receive the proximal portion of one of thelead body of FIG. 2, according to the invention;

FIG. 3C is a schematic view of one embodiment of a proximal portion ofthe lead body of FIG. 2, a lead extension, and the control module ofFIG. 2, the lead extension configured and arranged to couple the leadbody to the control module, according to the invention;

FIG. 4A is a schematic view of one embodiment of a portion of a controlmodule suitable for providing electrical signals to an electricalstimulation lead, the control module including an electronic subassemblydisposed in a casing and a feedthrough housing enabling current topropagate into the casing, according to the invention;

FIG. 4B is a schematic side view of one embodiment of a portion of thecontrol module of FIG. 4A, according to the invention;

FIG. 5A is a schematic view of another embodiment of the control moduleof FIG. 4A, the control module including a RF-diverting assemblydisposed in the feedthrough housing of the control module, according tothe invention;

FIG. 5B is a schematic cross-sectional side view of one embodiment ofthe RF-diverting assembly of FIG. 5A disposed in the control module ofFIG. 4A, according to the invention;

FIG. 6A is a schematic top perspective view of one embodiment of aRF-diverting assembly, the RF-diverting assembly including a feedthroughground, a plurality of conductive pads, and a plurality of capacitiveelements, according to the invention;

FIG. 6B is a schematic top perspective exploded view of one embodimentof the RF-diverting assembly of FIG. 6A, according to the invention;

FIG. 7A is a schematic top perspective view of one embodiment of theRF-diverting assembly of FIG. 6A disposed in a control module, where theRF-diverting assembly is coupled to a flex circuit disposed in thecontrol module, according to the invention;

FIG. 7B is a schematic top perspective view of one embodiment of theRF-diverting assembly of FIG. 6A disposed in the control module of FIG.7A, where the RF-diverting assembly is coupled to the flex circuit ofFIG. 7A and also to a feedthrough housing disposed in the controlmodule, according to the invention;

FIG. 8A is a schematic top perspective view of one embodiment of a basesuitable for facilitating fabrication of the RF-diverting assembly ofFIG. 6A, according to the invention;

FIG. 8B is a schematic top perspective view of one embodiment of thefeedthrough ground of FIG. 6A and the conductive pads of FIG. 6Adisposed on the base of FIG. 8A, according to the invention;

FIG. 8C is a schematic top perspective view of one embodiment of thecapacitive elements of FIG. 6A coupled to both the feedthrough ground ofFIG. 6A and the conductive pads of FIG. 6A which, in turn, are bothdisposed on the base of FIG. 8A, according to the invention;

FIG. 8D is schematic bottom perspective view of one embodiment of thefeedthrough ground of FIG. 6A, the capacitive elements of FIG. 6A, andthe conductive pads of FIG. 6A removed from the base of FIG. 8A, wherethe plurality of conductive pads are coupled to one another viaconnecting links, according to the invention;

FIG. 8E is schematic bottom perspective view of one embodiment of thefeedthrough ground of FIG. 6A, the capacitive elements of FIG. 6A, andthe conductive pads of FIG. 6A removed from the base of FIG. 8A, wherethe plurality of conductive pads are separated from one another alongthe connecting links of FIG. 8D, according to the invention;

FIG. 9A is a schematic top perspective view of another embodiment of aRF-diverting assembly, the RF-diverting assembly including a feedthroughground, a plurality of conductive pads coupled to the ground ring, and aplurality of capacitive elements, according to the invention;

FIG. 9B is a schematic top perspective exploded view of one embodimentof the RF-diverting assembly of FIG. 9A, according to the invention;

FIG. 9C is schematic bottom perspective view of one embodiment of thefeedthrough ground of FIG. 9A, the capacitive elements of FIG. 9A, andthe conductive pads of FIG. 9A, where the plurality of conductive padsare coupled to the feedthrough ground via connecting links, according tothe invention;

FIG. 9D is schematic bottom perspective view of one embodiment of thefeedthrough ground of FIG. 9A, the capacitive elements of FIG. 9A, andthe conductive pads of FIG. 9A, where the plurality of conductive padsare separated from the feedthrough ground along the connecting links ofFIG. 9C, according to the invention;

FIG. 10A is a schematic top perspective view of another embodiment of aRF-diverting assembly coupled to a flex circuit and to a feedthroughhousing, according to the invention;

FIG. 10B is a schematic top perspective exploded view of one embodimentof the RF-diverting assembly of FIG. 10A, the flex circuit of FIG. 10A,and the feedthrough housing of FIG. 10A to which the RF-divertingassembly couple, according to the invention;

FIG. 11A is a schematic top view of another embodiment of the controlmodule of FIG. 4A, the control module including a plurality of inductorsdisposed on conductive pathways extending within the control modulebetween a feedthrough housing and an electronic subassembly, accordingto the invention;

FIG. 11B is a schematic top perspective view of one embodiment of theinductors of FIG. 11A disposed in another embodiment of a controlmodule, according to the invention; and

FIG. 12 is a schematic overview of one embodiment of components of anelectrical stimulation system, according to the invention.

DETAILED DESCRIPTION

The present invention is directed to the area of implantable electricalstimulation systems and methods of making and using the systems. Thepresent invention is also directed to implantable electrical stimulationcontrol modules that modulate undesired propagation of current intoelectronic systems within the control modules, as well as methods ofmaking and using the control modules and electrical stimulation systems.

Suitable implantable electrical stimulation systems include, but are notlimited to, an electrode lead (“lead”) with one or more electrodesdisposed on a distal end of the lead and one or more terminals disposedon one or more proximal ends of the lead. Leads include, for example,deep brain stimulation leads, percutaneous leads, paddle leads, and cuffleads. Examples of electrical stimulation systems with leads are foundin, for example, U.S. Pat. Nos. 6,181,969; 6,516,227; 6,609,029;6,609,032; 6,741,892; 7,244,150; 7,672,734; 7,761,165; 7,949,395;7,974,706; 8,175,710; 8,224,450; and 8,364,278; and U.S. PatentApplication Publication No. 2007/0150036, all of which are incorporatedby reference.

FIG. 1 illustrates schematically one embodiment of an electricalstimulation system 100. The electrical stimulation system includes acontrol module (e.g., a stimulator or pulse generator) 102 and a lead103. The lead 103 including a paddle body 104 and one or more leadbodies 106 coupling the control module 102 to the paddle body 104. Thepaddle body 104 and the one or more lead bodies 106 form the lead 103.The paddle body 104 typically includes a plurality of electrodes 134that form an array of electrodes 133. The control module 102 typicallyincludes an electronic subassembly 110 and an optional power source 120disposed in a sealed housing 114. In FIG. 1, two lead bodies 106 areshown coupled to the control module 102.

The control module 102 typically includes one or more connectorassemblies 144 into which the proximal end of the one or more leadbodies 106 can be plugged to make an electrical connection via connectorcontacts (e.g., 316 in FIG. 3A) disposed in the connector assembly 144and terminals (e.g., 310 in FIG. 3A) on each of the one or more leadbodies 106. The connector contacts are coupled to the electronicsubassembly 110 and the terminals are coupled to the electrodes 134. InFIG. 1, two connector assemblies 144 are shown.

The one or more connector assemblies 144 may be disposed in a header150. The header 150 provides a protective covering over the one or moreconnector assemblies 144. The header 150 may be formed using anysuitable process including, for example, casting, molding (includinginjection molding), and the like. In addition, one or more leadextensions 324 (see FIG. 3C) can be disposed between the one or morelead bodies 106 and the control module 102 to extend the distancebetween the one or more lead bodies 106 and the control module 102.

It will be understood that the electrical stimulation system can includemore, fewer, or different components and can have a variety of differentconfigurations including those configurations disclosed in theelectrical stimulation system references cited herein. For example,instead of a paddle body 104, the electrodes 134 can be disposed in anarray at or near the distal end of a lead body 106′ forming apercutaneous lead 103, as illustrated in FIG. 2. The percutaneous leadmay be isodiametric along the length of the lead body 106″. The leadbody 106′ can be coupled with a control module 102′ with a singleconnector assembly 144.

The electrical stimulation system or components of the electricalstimulation system, including one or more of the lead bodies 106, thecontrol module 102, and, in the case of a paddle lead, the paddle body104, are typically implanted into the body of a patient. The electricalstimulation system can be used for a variety of applications including,but not limited to, spinal cord stimulation, brain stimulation, neuralstimulation, muscle activation via stimulation of nerves innervatingmuscle, and the like.

The electrodes 134 can be formed using any conductive, biocompatiblematerial. Examples of suitable materials include metals, alloys,conductive polymers, conductive carbon, and the like, as well ascombinations thereof. In at least some embodiments, one or more of theelectrodes 134 are formed from one or more of: platinum, platinumiridium, palladium, titanium, or rhenium.

The number of electrodes 134 in the array of electrodes 133 may vary.For example, there can be two, three, four, five, six, seven, eight,nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, or moreelectrodes 134. As will be recognized, other numbers of electrodes 134may also be used. In FIG. 1, sixteen electrodes 134 are shown. Theelectrodes 134 can be formed in any suitable shape including, forexample, round, oval, triangular, rectangular, pentagonal, hexagonal,heptagonal, octagonal, or the like.

The electrodes of the paddle body 104 or one or more lead bodies 106 aretypically disposed in, or separated by, a non-conductive, biocompatiblematerial including, for example, silicone, polyurethane, and the like orcombinations thereof. The paddle body 104 and one or more lead bodies106 may be formed in the desired shape by any process including, forexample, molding (including injection molding), casting, and the like.Electrodes and connecting wires can be disposed onto or within a paddlebody either prior to or subsequent to a molding or casting process. Thenon-conductive material typically extends from the distal end of thelead 103 to the proximal end of each of the one or more lead bodies 106.The non-conductive, biocompatible material of the paddle body 104 andthe one or more lead bodies 106 may be the same or different. The paddlebody 104 and the one or more lead bodies 106 may be a unitary structureor can be formed as two separate structures that are permanently ordetachably coupled together.

Terminals (e.g., 310 in FIG. 3A) are typically disposed at the proximalend of the one or more lead bodies 106 for connection to correspondingconductive contacts (e.g., 316 in FIG. 3A) in connector assemblies(e.g., 144 in FIG. 1) disposed on, for example, the control module 102(or to other devices, such as conductive contacts on a lead extension,an operating room cable, a splitter, an adaptor, or the like).

Conductive wires (not shown) extend from the terminals (e.g., 310 inFIG. 3A) to the electrodes 134. Typically, one or more electrodes 134are electrically coupled to a terminal (e.g., 310 in FIG. 3A). In someembodiments, each terminal (e.g., 310 in FIG. 3A) is only coupled to oneelectrode 134.

The conductive wires may be embedded in the non-conductive material ofthe lead or can be disposed in one or more lumens (not shown) extendingalong the lead. In some embodiments, there is an individual lumen foreach conductive wire. In other embodiments, two or more conductive wiresmay extend through a lumen. There may also be one or more lumens (notshown) that open at, or near, the proximal end of the lead, for example,for inserting a stylet rod to facilitate placement of the lead within abody of a patient. Additionally, there may also be one or more lumens(not shown) that open at, or near, the distal end of the lead, forexample, for infusion of drugs or medication into the site ofimplantation of the paddle body 104. The one or more lumens may,optionally, be flushed continually, or on a regular basis, with saline,epidural fluid, or the like. The one or more lumens can be permanentlyor removably sealable at the distal end.

As discussed above, the one or more lead bodies 106 may be coupled tothe one or more connector assemblies 144 disposed on the control module102. The control module 102 can include any suitable number of connectorassemblies 144 including, for example, two three, four, five, six,seven, eight, or more connector assemblies 144. It will be understoodthat other numbers of connector assemblies 144 may be used instead. InFIG. 1, each of the two lead bodies 106 includes eight terminals thatare shown coupled with eight conductive contacts disposed in a differentone of two different connector assemblies 144.

FIG. 3A is a schematic side view of one embodiment of a plurality ofconnector assemblies 144 disposed on the control module 102. In at leastsome embodiments, the control module 102 includes two connectorassemblies 144. In at least some embodiments, the control module 102includes four connector assemblies 144. In FIG. 3A, proximal ends 306 ofthe plurality of lead bodies 106 are shown configured and arranged forinsertion to the control module 102. FIG. 3B is a schematic side view ofone embodiment of a single connector assembly 144 disposed on thecontrol module 102′. In FIG. 3B, the proximal end 306 of the single leadbody 106′ is shown configured and arranged for insertion to the controlmodule 102′.

In FIGS. 3A and 3B, the one or more connector assemblies 144 aredisposed in the header 150. In at least some embodiments, the header 150defines one or more ports 304 into which the proximal end(s) 306 of theone or more lead bodies 106/106′ with terminals 310 can be inserted, asshown by directional arrows 312, in order to gain access to theconnector contacts disposed in the one or more connector assemblies 144.

The one or more connector assemblies 144 each include a connectorhousing 314 and a plurality of connector contacts 316 disposed therein.Typically, the connector housing 314 defines a port (not shown) thatprovides access to the plurality of connector contacts 316. In at leastsome embodiments, one or more of the connector assemblies 144 furtherincludes a retaining element 318 configured and arranged to fasten thecorresponding lead body 106/106′ to the connector assembly 144 when thelead body 106/106′ is inserted into the connector assembly 144 toprevent undesired detachment of the lead body 106/106′ from theconnector assembly 144. For example, the retaining element 318 mayinclude an aperture through which a fastener (e.g., a set screw, pin, orthe like) may be inserted and secured against an inserted lead body106/106′.

When the one or more lead bodies 106/106′ are inserted into the one ormore ports 304, the connector contacts 316 can be aligned with theterminals 310 disposed on the one or more lead bodies 106/106′ toelectrically couple the control module 102 to the electrodes (134 ofFIG. 1) disposed at a distal end of the one or more lead bodies 106.Examples of connector assemblies in control modules are found in, forexample, U.S. Pat. Nos. 7,244,150 and 8,224,450, which are incorporatedby reference.

In at least some embodiments, the electrical stimulation system includesone or more lead extensions. The one or more lead bodies 106/106′ can becoupled to one or more lead extensions which, in turn, are coupled tothe control module 102/102′. In FIG. 3C, a lead extension connectorassembly 322 is disposed on a lead extension 324. The lead extensionconnector assembly 322 is shown disposed at a distal end 326 of the leadextension 324. The lead extension connector assembly 322 includes acontact housing 328. The contact housing 328 defines at least one port330 into which a proximal end 306 of the lead body 106′ with terminals310 can be inserted, as shown by directional arrow 338. The leadextension connector assembly 322 also includes a plurality of connectorcontacts 340. When the lead body 106′ is inserted into the port 330, theconnector contacts 340 disposed in the contact housing 328 can bealigned with the terminals 310 on the lead body 106 to electricallycouple the lead extension 324 to the electrodes (134 of FIG. 1) disposedat a distal end (not shown) of the lead body 106′.

The proximal end of a lead extension can be similarly configured andarranged as a proximal end of a lead body. The lead extension 324 mayinclude a plurality of conductive wires (not shown) that electricallycouple the connector contacts 340 to terminal on a proximal end 348 ofthe lead extension 324. The conductive wires disposed in the leadextension 324 can be electrically coupled to a plurality of terminals(not shown) disposed on the proximal end 348 of the lead extension 324.In at least some embodiments, the proximal end 348 of the lead extension324 is configured and arranged for insertion into a lead extensionconnector assembly disposed in another lead extension. In otherembodiments (as shown in FIG. 3C), the proximal end 348 of the leadextension 324 is configured and arranged for insertion into theconnector assembly 144 disposed on the control module 102′.

It will be understood that the control modules 102/102′ can receiveeither lead bodies 106/106′ or lead extensions 324. It will also beunderstood that the electrical stimulation system 100 can include aplurality of lead extensions 224. For example, each of the lead bodies106 shown in FIGS. 1 and 3A can, alternatively, be coupled to adifferent lead extension 224 which, in turn, are each coupled todifferent ports of a two-port control module, such as the control module102 of FIGS. 1 and 3A.

FIG. 4A is a schematic view of one embodiment of a portion of a controlmodule 402 suitable for providing electrical signals to an electricalstimulation lead (e.g., lead 103 of FIG. 1 or 2). FIG. 4B is a schematiccross-sectional side view of one embodiment of a portion of the controlmodule 402. The control module 402 includes an electronic subassembly406 disposed in a sealed control module casing 408. The electronicsubassembly 406 includes a pulse generator 410 for providing electricalsignals. The electronic subassembly 406 can be mounted on a printedcircuit board (“PCB”) 420. Optionally, the control module 402 includes apower source 412 (such as a battery) coupled to the electronicsubassembly 406.

A feedthrough housing 430 is disposed along a wall of the control modulecasing 408. A plurality of feedthrough pins, such as feedthrough pin440, are at least partially disposed in the feedthrough housing 430 andprovide conductive paths across the sealed control module casing 408. Inat least some embodiments, a connector assembly 470 is disposed on anexterior portion of the control module casing 408. The connectorassembly 470 may, optionally, be disposed in a header 450 (See e.g., 150in each of FIGS. 1-3C). In which case, in at least some embodiments thefeedthrough housing 430 is disposed along a portion of the controlmodule casing 408 that abuts the header 450. The connector assembly 470can be configured and arranged to receive one or more leads 480.Optionally, the connector assembly 430 can be configured and arranged toreceive one or more lead extensions (see e.g., 324 in FIG. 3C) inaddition to, or in lieu of, one or more leads 480.

In at least some embodiments, the feedthrough pin 440 provide conductivepaths across the sealed control module casing 408 between the connectorassembly 470 and the electronic subassembly 406. Thus, the feedthroughpins 440 can be used for electrically coupling the electrodes disposedalong the lead with the electronic subassembly 406 when the lead 480 (orlead extension) is inserted into the connector assembly 470.

The portions of the feedthrough pins 440 external to the control modulecasing 408 couple electrically with connector contacts, such asconnector contact 490, disposed in the connector assembly 470 which, inturn, are configured and arranged to couple electrically with terminals495 of the insertable lead 480 (or lead extension).

The portions of the feedthrough pins 440 disposed within the controlmodule casing 408 couple to the electronic subassembly 406 viaconductive pathways, such as conductive pathway 434. In at least someembodiments, at least a portion of a length of each of the conductivepathways 434 is formed on a non-conductive substrate, such as a flexcircuit 444, or the like. In at least some embodiments, at least aportion of the lengths of the conductive pathways are formed on the PCB420. In at least some embodiments, at least a portion of the lengths ofthe conductive pathways are formed on the flex circuit 444 and the PCB420. In at least some embodiments, the number of conductive pathways 434is equal to the number of feedthrough pins 440.

The control module casing 408 is at least partially formed from one ormore conductive materials 409 (e.g., one or more metals, alloys,conductive polymers, or the like). In at least some embodiments, thecontrol module casing 408 is entirely formed from one or more conductivematerials 409. In at least some alternate embodiments, the controlmodule casing 408 is formed partially from one or more conductivematerials and partially from one or more non-conductive materials. Whenthe control module casing 408 is formed partially from one or moreconductive materials and partially from one or more non-conductivematerials, the conductive and non-conductive materials can be arrangedin any suitable configuration. In at least some embodiments, the controlmodule casing 408 is formed from one or more conductive regions (e.g.,one or more plates, or the like) surrounded by one or morenon-conductive materials.

In at least some embodiments, the conductivity of the conductiveportion(s) of the control module casing 408 can be used to ground theelectronic subassembly 406. In FIG. 4A, the electronic subassembly 406is shown grounded to the conductive portion 409 of the control modulecasing 408 via one or more ground lines 448. At least some of the wallsof the feedthrough housing 430 are at least partially formed from one ormore conductive materials 431 (e.g., one or more metals, alloys,conductive polymers, or the like). Non-conductive material is disposedalong the interior of the feedthrough housing 430 to electricallyisolate the feedthrough pins 440 from one another and from theconductive portions of the walls 431 of the feedthrough housing 430.

Conventional electrical stimulation systems may be potentially unsafefor use with magnetic resonance imaging (“MRI”) due to the effects ofelectromagnetic fields in an MRI environment. One mechanism forgenerating an electrical interaction between the electrical stimulationsystem and RF irradiation is common-mode coupling of the appliedelectromagnetic fields. This coupling can be modeled as a series ofdistributed sources along an elongated conductive structure, such as alead, or conductors within a lead. Common-mode induced RF currents canreach amplitudes of greater than one ampere in MRI environments. Suchcurrents can cause heating and potentially damaging conditions withinelectronic circuits.

Some of the deleterious effects of RF irradiation may include, forexample, inducing current in the lead, causing undesired heating of thelead that may potentially cause tissue damage, undesired or unexpectedoperation of electronic components, or premature failure of electroniccomponents. Additionally, when an electrical stimulation system is usedwithin an MRI scanner environment, the electrical interactions betweenthe electrical stimulation system and the MRI may cause distortions inimages formed by the MRI system.

When the lead (or lead extension) is inserted into the connectorassembly, and when the electrical stimulation system is implanted into apatient and exposed to RF irradiation (e.g., during an MRI procedure),undesired induced currents can propagate along the lead and along theconductive pathways of the control module to the electronic subassembly.

Turning to FIG. 5A, as herein described an RF-diverting assembly isdisposed in the control module to filter out RF-induced currentspropagating into the control module from the lead when the lead isreceived by the control module (see e.g., FIGS. 1 and 2). TheRF-diverting assembly diverts the undesired RF-induced current beforethe RF-induced current reaches the electronic subassembly, therebyreducing, or even preventing, damage to the system electronics caused byexposure to RF irradiation. In at least some embodiments, theRF-diverting assembly diverts the undesired RF-induced current whileproviding little, if any, interference with the propagation ofoperational electrical signals between the electrodes and the electricalsubassembly.

FIG. 5A is a schematic top view of one embodiment of a RF-divertingassembly 501 disposed in the control module 402. FIG. 5B is a schematiccross-sectional side view of one embodiment of the RF-diverting assembly501 disposed in the control module 402. In at least some embodiments,the RF-diverting assembly 501 is configured and arranged to shunt most,if not all, of the undesired induced current to the conductive portion431 of the feedthrough housing 430 which, in turn, shunts the inducedcurrent to the conductive portion 409 of the control module casing 408.

In at least some embodiments, the RF-diverting assembly 501 is alsoconfigured and arranged to enable most, if not all, of the operationalcurrent to propagate along the feedthrough pins 440, between theconnector assembly 470 and the electronic subassembly 406, without beingdiverted. In at least some embodiments, the RF-diverting assembly 501 iscoupled to each of the feedthrough pins 440. In at least someembodiments, the RF-diverting assembly 501 is coupled to each of theconductive pathways 434. In at least some embodiments, the RF-divertingassembly 501 is coupled to each of the feedthrough pins 440 and to eachof the conductive pathways 434. In at least some embodiments, theRF-diverting assembly 501 is coupled to the flex circuit 444. In atleast some embodiments, the RF-diverting assembly 501 is coupled to thefeedthrough housing 430.

The control module 402 shown in FIGS. 4A-5B is configured to receivecurrent along up to four feedthrough pins. Consequently, theRF-diverting assembly 501 shown in FIGS. 5A-5B is configured andarranged to disperse induced current propagating along up to fourfeedthrough pins. The control module 402 can be configured to receiveleads (or lead extensions) with any suitable number ofterminals/electrodes for providing efficacious stimulation to a patientincluding, for example, one, two, three, four, five, six, seven, eight,nine, ten, eleven, twelve, fourteen, sixteen, eighteen, twenty,twenty-four, twenty-eight, thirty-two, or more terminals/electrodes. Itwill be understood that the RF-diverting assembly 501 can be adapted, asdesired, to disperse current propagating along each of the feedthroughpins, regardless of the number of feedthrough pins.

FIG. 6A is a schematic top perspective view of one embodiment of theRF-diverting assembly 601. FIG. 6B is a schematic top perspectiveexploded view of one embodiment of the RF-diverting assembly 601. TheRF-diverting assembly 601 includes a feedthrough ground 602; a pluralityof conductive pads, such as conductive pad 604, arranged into an array614 of conductive pads; and a plurality of capacitive elements, such ascapacitive element 606, arranged into an array 616 of conductive pads.

In at least some embodiments, the conductor pads 604 are electricallycoupled to at least one of the feedthrough pins 440 or the conductivepathways 434. The capacitive elements 606 extend between the conductorpads 606 and the feedthrough ground 602 and provide a relatively-lowresistance path for undesired current to propagate along. Thefeedthrough ground 602 is electrically coupled to the conductive portion431 of the feedthrough housing 430 which, in turn, is electricallycoupled to the conductive portion 409 of the control module casing 408.

Any suitable capacitive element 606 may be used. In FIG. 6A (and inother figures), the capacitive elements 606 are shown with a dielectric632 disposed between a first plate 634 and a second plate 636. In atleast some embodiments, the capacitive element 606 can be disposed onthe RF-diverting assembly 601 such that each of the first plates 634 iscoupled to a different one of the conductor pads 604 and each of thesecond plates 636 is coupled to the feedthrough ground 602.

The capacitive elements 606 can have any capacitance suitable forproviding a low impedance path for induced currents, while providing ahigh impedance path for operational currents. During a typical MRIprocedure, a patient may be exposed to frequencies (e.g., approximately64 MHz to 128 MHz) that are much higher than the operational frequenciesof the electronic stimulation system. Accordingly, in at least someembodiments the capacitive elements 606 are configured and arranged tofilter out frequencies above (or below) the operational frequencies ofthe electrical stimulation system.

In at least some embodiments, the capacitance of each of the capacitiveelements 606 is no greater than 2000 pF. In at least some embodiments,the capacitance of each of the capacitive elements 606 is no less than1000 pF. In at least some embodiments, the capacitance of each of thecapacitive elements 606 is in a range that is no greater than 2000 pFand is no less than 1000 pF.

Optionally, adhesive 608 may be applied to the current-dispendingapparatus 601 to provide mechanical support for the RF-divertingassembly 601. For example, in at least some embodiments, adhesive 608 isdisposed between adjacent capacitive elements 606 to provide additionalmechanical support between the adjacent capacitive elements 606. In atleast some embodiments, the adhesive 608 is disposed between adjacentfirst plates 634 of the capacitive elements 606.

The RF-diverting assembly 601 can be adapted to shunt currentpropagating along any suitable number of feedthrough pins. In FIGS.6A-6B (and in other figures), the RF-diverting assembly 601 isconfigured to shunt current propagating along up to sixteen feedthroughpins. The RF-diverting assembly 601 can include any suitable number ofcapacitive elements. The number of capacitive elements disposed on theRF-diverting assembly 601 can be fewer than, equal to, or greater thanthe number of feedthrough pins of the control module 402. TheRF-diverting assembly 601 can include any suitable number of conductivepads. The number of conductive pads disposed on the RF-divertingassembly 601 can be fewer than, equal to, or greater than the number offeedthrough pins of the control module 402.

Optionally, the feedthrough ground 602 includes one or more couplingpads 686 for facilitating coupling of the feedthrough ground 602 to theone or more conductive portions 431 of the feedthrough housing 430. InFIGS. 6A-6B (and in other figures), the one or more coupling pads 686are disposed along opposing ends of the feedthrough housing 430.

In at least some embodiments, the feedthrough ground 602 is alsoconfigured and arranged to mechanically couple to the flex circuit 444.The feedthrough ground 602 can be formed from any non-magnetic,conductive material suitable for coupling to both the feedthroughhousing 430 and the flex circuit 444. In at least some embodiments, theconductive portion 431 of the feedthrough housing 430 is formed fromtitanium. In which case, it may be advantageous to form the feedthroughground 502 from at least one of nickel or nickel alloy so that thefeedthrough ground 602 can be coupled (e.g., resistant welded, laserwelded, or the like) directly to the conductive portion 431 of thefeedthrough housing 430. It may also be advantageous to form thefeedthrough ground 602 from nickel so that the feedthrough ground 602can be coupled (e.g., soldered, adhesively coupled with a conductiveadhesive, or the like) directly to the flex circuit 444.

The feedthrough ground 602 can be formed in any shape suitable forreceiving current from each of the capacitive elements 606 and enablingpropagation of that current to the feedthrough housing 430. In at leastsome embodiments, the feedthrough ground 602 is formed as a closed loop.In at least some embodiments, the feedthrough ground 602 is formed as anelongated closed loop. In at least some embodiments, the feedthroughground 602 is formed as a closed loop configured and arranged to receivethe plurality of capacitive elements 606.

In at least some embodiments, at least some of the plurality ofconductive pads 604 are coupled to one another via connecting links 624prior to insertion of the RF-diverting assembly 601. In at least someembodiments, prior to insertion of the RF-diverting assembly 601 each ofthe plurality of conductive pads is coupled to one another such thateach of the conductive pads 604 form a single unit. In at least someembodiments, each of the plurality of conductive pads 604 defines anaperture 634. In at least some embodiments, at least some of theconductive pads 604 are arranged in the same configuration as thefeedthrough pins 440 of the control module 402.

FIG. 7A is a schematic top perspective view of one embodiment of acontrol module 702 with a portion of the casing (see e.g., 408 in FIGS.4A-5B) removed. The control module 702 includes a flex circuit 744. TheRF-diverting assembly 601 is disposed on the flex circuit 744.Conductive pathways 734 disposed on the flex circuit 744 electricallycouple the RF-diverting assembly 601 to the electronic subassembly 706.FIG. 7B is a schematic top perspective view of one embodiment of aportion of the control module 702. The control module 702 includes apartially-opened casing 708 and a feedthrough housing 730 disposed on aninner surface of the casing 708.

The RF-diverting assembly 601 is coupled to the flex circuit 744 andalso to the feedthrough housing 730. In FIG. 7B, the RF-divertingassembly 601 is coupled to the feedthrough housing 430 such that theflex circuit 744 is sandwiched between the RF-diverting assembly 601 andthe feedthrough housing 430.

The RF-diverting assembly 601 can be formed in any suitable manner.FIGS. 8A-8E illustrate one of many possible ways to form theRF-diverting assembly 601. FIG. 8A is a schematic top perspective viewof one embodiment of a base 802 suitable for facilitating fabrication ofthe RF-diverting assembly 601. In at least some embodiments, the base802 is configured to provide consistent spacing between components ofthe RF-diverting assembly 601 prior to coupling the components together.

The base 802 includes a major surface 804 along which a plurality ofpins, such as pin 806, extend. In at least some embodiments, at leastsome of the pins 806 are arranged along the major surface 804 in thesame configuration as the feedthrough pins 440 of the control module402. The major surface 804 and the pins 806 can be formed from anysuitable non-solderable metallic material including, for example,magnesium, chromium, titanium, stainless steel, aluminum, or the like.

FIG. 8B is a schematic top perspective view of one embodiment of thefeedthrough ground 602 and the conductive pads 604 disposed on the majorsurface 804 of the base 802. In FIG. 8B, the pins 806 are spaced alongthe major surface 804 so that when the feedthrough ground 602 and theconductive pads 604 are disposed on the base 802 the feedthrough ground602 and the conductive pads 604 are particularly aligned with oneanother. In at least some embodiments, the conductive pads 604 can bedisposed on the base 802 such that the apertures 634 of the conductivepads 604 mate with at least some of the pins 806. In FIG. 8B, thefeedthrough ground 602 and the conductive pads 604 are aligned such thatthe conductive pads 604 are disposed within the feedthrough ground 602.

In at least some embodiments, when the feedthrough ground 602 and theconductive pads 604 are aligned (as can be facilitated by the base 802),the capacitive elements can be used to couple each of the conductivepads 604 to the feedthrough ground 602. FIG. 8C is a schematic topperspective view of one embodiment of the capacitive elements 606disposed on both the feedthrough ground 602 and the conductive pads 604.The capacitive elements 606 can be coupled to the feedthrough ground 602and the conductive pads 604 in any suitable manner (e.g., soldering,adhesively coupled with conductive adhesive, or the like). In at leastsome embodiments, adjacent capacitive elements 606 of the plurality ofcapacitive elements 606 are coupled together via adhesive (608 in FIG.6B) to provide mechanical reinforcement.

In at least some embodiments, when the capacitive elements 606 arecoupled to the feedthrough ground 602 and the conductive pads 604 andthe adhesive is set (if applicable), the capacitive elements 606,conductive pads 604, and feedthrough ground 602 are removed from thebase 802. FIG. 8D is schematic bottom perspective view of one embodimentof the capacitive elements 606, conductive pads 604, and feedthroughground 602. As shown in FIG. 8D, the capacitive elements 606, conductivepads 604, and feedthrough ground 602 have been removed from the base802. Adjacent conductive pads 604 are connected to one another via theconnecting links 624.

In at least some embodiments, when the capacitive elements 606,conductive pads 604, and feedthrough ground 602 are removed from thebase 802, the conductive pads 604 are separated from one another. FIG.8E is schematic bottom view of one embodiment of the plurality ofconductive pads 604 separated from one another by removal of theconnecting links 624. The conductive pads 604 can be separated from oneanother along the connecting links 624 in any suitable manner including,for example, laser cutting.

Turning to FIG. 9A, in at least some embodiments the conductive pads arecoupled to the feedthrough ground prior to assembly of the RF-divertingassembly. In at least some embodiments, prior to assembly of theRF-diverting assembly the conductive pads are coupled to the feedthroughground in addition to being coupled to one another. In at least someembodiments, prior to assembly of the RF-diverting assembly theconductive pads are coupled to the feedthrough ground in lieu of beingcoupled to one another.

FIG. 9A is a schematic top perspective view of another embodiment of aRF-diverting assembly 901. FIG. 9B is a schematic top perspectiveexploded view of one embodiment of the RF-diverting assembly 901. TheRF-diverting assembly 901 includes a feedthrough ground 902; a pluralityof conductive pads, such as conductive pad 904, arranged into an array914 of conductive pads; and a plurality of capacitive elements, such ascapacitive element 906, arranged into an array 916 of conductive pads.Optionally, adhesive 908 may be applied to the current-dispendingapparatus 901 to provide mechanical support. For example, in at leastsome embodiments adhesive 908 is disposed between adjacent capacitiveelements 906.

As shown in FIG. 9B, the conductive pads 904 are coupled to thefeedthrough ground 902 prior to coupling the capacitive elements 906 tothe conductive pads 904 and the feedthrough ground 902. In at least someembodiments, the conductive pads 904 are coupled to the feedthroughground 902 via connecting links, such as connecting link 924. In atleast some embodiments, the conductive pads 904 are arranged in the sameconfiguration as the feedthrough pins 440 of the control module 402.

When, as shown in FIG. 9B, the conductive pads 904 are coupled to thefeedthrough ground 902 prior to coupling the capacitive elements 906 tothe conductive pads 904 and the feedthrough ground 902 a base (see e.g.,base 802 in FIG. 8A) may not be needed during the manufacturing processto facilitate alignment of the conductive pads 904 with the feedthroughground 902.

FIG. 9C is schematic bottom perspective view of one embodiment of eachof the conductive pads 904 coupled to the feedthrough ground 902 via thecapacitive elements 906. The conductive pads 904 are also coupled to thefeedthrough ground 902 via the connecting links 924. FIG. 9D isschematic bottom perspective view of one embodiment of each of theconductive pads 904 coupled to the feedthrough ground 902 via thecapacitive elements 906. The connecting links 924 have been removed toseparate the direct connection between the conductive pads 904 and thefeedthrough ground 902 so that the conductive pads 904 are only coupledto the feedthrough ground 902 via the capacitive elements 906. Theconnecting link 924 can be removed using any suitable manner including,for example, laser cutting.

Turning to FIG. 10A, in at least some embodiments the conductive padsand the capacitors are disposed directly on the flex circuit. In atleast some embodiments, the conductive pads and the capacitors aredisposed on a first major surface of the flex circuit and thefeedthrough ground is disposed on an opposing second major surface ofthe flex circuit. In other words, in at least some embodiments the flexcircuit is sandwiched between the conductive pads/capacitive elementsand the feedthrough ground.

FIG. 10A is a schematic top perspective view of one embodiment of theflex circuit 1044, a RF-diverting assembly 1001, and the feedthroughhousing 1030. FIG. 10B is a schematic top perspective exploded view ofone embodiment of the flex circuit 1044, the RF-diverting assembly 1001,and the feedthrough housing 1030. A plurality of conductive pathways,such as conductive pathway 1034, are disposed on the flex circuit 1044.A plurality of feedthrough pins, such as feedthrough pin 1040, extendfrom the feedthrough housing 1030.

The RF-diverting assembly 1001 includes a plurality of capacitiveelements, such as capacitive element 1006; a plurality of first contactregions, such as first contact region 1004 a; a plurality of secondcontact regions, such as second contact region 1004 b; and a feedthroughground 1002. In FIGS. 10A-10B, the first contact regions 1004 a, thesecond contact regions 1004 b, and the capacitive elements 1006 are eachcoupled directly to a first major surface 1052 of the flex circuit 1044.

The first contact regions 1004 a, the second contact regions 1004 b, andthe capacitive elements 1006 are configured such that the capacitiveelements 1006 each electrically couple one of the first contact regions1004 a to a different one of the second contact regions 1004 b. Thefirst contact regions 1004 a are each configured to electrically couple(e.g., welding, soldering, conductive adhesive, or the like) to one ofthe feedthrough pins 1040 (and also to one of the conductive pathways1034. The second contact regions 1004 b are each configured and arrangedto electrically couple (e.g., welding, conductive adhesive, or the like)with the feedthrough ground 1002 which, in turn, is coupleable to thefeedthrough housing 1030. The contact regions 1004 a and 1004 b can beformed on the flex circuit 1044 using standard circuit-formingtechniques (e.g., photolithography, or the like). In at least someembodiments, the first contact regions 1004 a and the second contactregions 1004 a are formed as conductive pads.

In FIGS. 10A-10B, the first contact regions 1004 a each define anaperture extending through the flex circuit 1044 for coupling the firstcontact regions 1004 a (disposed on the first major surface 1052 of theflex circuit 1044) with the feedthrough pins 1040 (which extend throughthe flex circuit 1044 from an opposing second major surface of the flexcircuit 1044). In FIGS. 10A-10B, the second contact regions 1004 b eachdefine an aperture extending through the flex circuit 1044 for couplingthe second contact regions 1004 b (disposed on the first major surface1052 of the flex circuit 1044) with the feedthrough ground 1002 (whichis coupled to the opposing second major surface of the flex circuit1044).

The capacitive elements 1006, the first contact regions 1004 a, and thesecond contact regions 1004 b can be coupled to the flex circuit 1044 inany suitable manner including, for example, soldering, conductiveadhesive, or the like. The feedthrough ground 1002 can be coupled to thefeedthrough housing 1030 in any suitable manner including, for example,welding, brazing, or the like. The feedthrough ground 1002 can becoupled to the flex circuit 1044 in any suitable manner including, forexample, welding, brazing, conductive adhesive, or the like. Thefeedthrough ground 1002 can be coupled to the flex circuit 1044 afterthe feedthrough ground 1002 is coupled to the feedthrough housing 1030.

In at least some embodiments, the feedthrough housing 1020 is formedfrom a material (e.g., titanium, or the like) that cannot be soldereddirectly to the flex circuit 1044. In at least some embodiments, thefeedthrough ground 1002 is sputtered onto the feedthrough housing 1030using any suitable metallic material including, for example, gold,silver, palladium, nickel, or the like. In which case, the sputteredfeedthrough ground 1002 may be soldered directly to the flex circuit1044.

Turning to FIG. 11A-11B, in at least some embodiments the RF-divertingassembly includes a plurality of inductors. Since the operationalfrequencies of the electrical stimulation system are much lower than theoperational frequencies of a typical MRI system, inductors can beselected to block the flow of induced current at the comparatively-highfrequencies of the MRI, while causing little or no effect to thecomparatively-low operational frequencies of the electrical stimulationsystem.

FIG. 11A is a schematic diagram of another embodiment of the controlmodule 402. A plurality of inductors, such as inductor 1104, aredisposed along the conductive pathways 434. The inductors 1104 may bedisposed at any suitable location along a length of the conductivepathways 434. In FIG. 11A, the inductors 1104 are shown disposed alongthe flex circuit 444. The inductors 1104 can be formed in any suitablemanner including, for example, etching one or more inductors 1104 intothe flex circuit 444, or attaching one or more inductors onto the flexcircuit 444.

FIG. 11B is a schematic top perspective view of one embodiment of theRF-diverting assembly 601 coupled to a flex circuit 1144 of a controlmodule 1102. In FIG. 11B, the RF-diverting assembly 601 includes aplurality of inductive elements, such as inductor 1104 disposed on theflex circuit 1144. In FIG. 11B, the inductors 1104 are shown as aplurality of loops. In at least some embodiments, one or more of theconductive pads 604 are coupled directly to one or more of the inductiveelements 1104.

The above-described embodiments of the RF-diverting assembly are easy tomanufacture, as compared to conventional filters. The above-describedembodiments of the RF-diverting assembly are inexpensive to manufacture,as compared to conventional filters. Additionally, the above-describedembodiments of the current-dispersing element have volumetric profilesthat are significantly smaller than other conventional filters.

FIG. 12 is a schematic overview of one embodiment of components of anelectrical stimulation system 1200 including an electronic subassembly1210 disposed within a control module. It will be understood that theelectrical stimulation system can include more, fewer, or differentcomponents and can have a variety of different configurations includingthose configurations disclosed in the stimulator references citedherein.

Some of the components (for example, power source 1212, antenna 1218,receiver 1202, and processor 1204) of the electrical stimulation systemcan be positioned on one or more circuit boards or similar carrierswithin a sealed housing of an implantable pulse generator, if desired.Any power source 1212 can be used including, for example, a battery suchas a primary battery or a rechargeable battery. Examples of other powersources include super capacitors, nuclear or atomic batteries,mechanical resonators, infrared collectors, thermally-powered energysources, flexural powered energy sources, bioenergy power sources, fuelcells, bioelectric cells, osmotic pressure pumps, and the like includingthe power sources described in U.S. Pat. No. 7,437,193, incorporatedherein by reference.

As another alternative, power can be supplied by an external powersource through inductive coupling via the optional antenna 1218 or asecondary antenna. The external power source can be in a device that ismounted on the skin of the user or in a unit that is provided near theuser on a permanent or periodic basis.

If the power source 1212 is a rechargeable battery, the battery may berecharged using the optional antenna 1218, if desired. Power can beprovided to the battery for recharging by inductively coupling thebattery through the antenna to a recharging unit 1216 external to theuser. Examples of such arrangements can be found in the referencesidentified above.

In one embodiment, electrical current is emitted by the electrodes 134on the paddle or lead body to stimulate nerve fibers, muscle fibers, orother body tissues near the electrical stimulation system. A processor1204 is generally included to control the timing and electricalcharacteristics of the electrical stimulation system. For example, theprocessor 1204 can, if desired, control one or more of the timing,frequency, strength, duration, and waveform of the pulses. In addition,the processor 1204 can select which electrodes can be used to providestimulation, if desired. In some embodiments, the processor 1204 mayselect which electrode(s) are cathodes and which electrode(s) areanodes. In some embodiments, the processor 1204 may be used to identifywhich electrodes provide the most useful stimulation of the desiredtissue.

Any processor can be used and can be as simple as an electronic devicethat, for example, produces pulses at a regular interval or theprocessor can be capable of receiving and interpreting instructions froman external programming unit 1208 that, for example, allows modificationof pulse characteristics. In the illustrated embodiment, the processor1204 is coupled to a receiver 1202 which, in turn, is coupled to theoptional antenna 1218. This allows the processor 1204 to receiveinstructions from an external source to, for example, direct the pulsecharacteristics and the selection of electrodes, if desired.

In one embodiment, the antenna 1218 is capable of receiving signals(e.g., RF signals) from an external telemetry unit 1206 which isprogrammed by a programming unit 1208. The programming unit 1208 can beexternal to, or part of, the telemetry unit 1206. The telemetry unit1206 can be a device that is worn on the skin of the user or can becarried by the user and can have a form similar to a pager, cellularphone, or remote control, if desired. As another alternative, thetelemetry unit 1206 may not be worn or carried by the user but may onlybe available at a home station or at a clinician's office. Theprogramming unit 1208 can be any unit that can provide information tothe telemetry unit 1206 for transmission to the electrical stimulationsystem 1200. The programming unit 1208 can be part of the telemetry unit1206 or can provide signals or information to the telemetry unit 1206via a wireless or wired connection. One example of a suitableprogramming unit is a computer operated by the user or clinician to sendsignals to the telemetry unit 1206.

The signals sent to the processor 1204 via the antenna 1218 and receiver1202 can be used to modify or otherwise direct the operation of theelectrical stimulation system. For example, the signals may be used tomodify the pulses of the electrical stimulation system such as modifyingone or more of pulse duration, pulse frequency, pulse waveform, andpulse strength. The signals may also direct the electrical stimulationsystem 1200 to cease operation, to start operation, to start chargingthe battery, or to stop charging the battery. In other embodiments, thestimulation system does not include an antenna 1218 or receiver 1202 andthe processor 1204 operates as programmed.

Optionally, the electrical stimulation system 1200 may include atransmitter (not shown) coupled to the processor 1204 and the antenna1218 for transmitting signals back to the telemetry unit 1206 or anotherunit capable of receiving the signals. For example, the electricalstimulation system 1200 may transmit signals indicating whether theelectrical stimulation system 1200 is operating properly or not orindicating when the battery needs to be charged or the level of chargeremaining in the battery. The processor 1204 may also be capable oftransmitting information about the pulse characteristics so that a useror clinician can determine or verify the characteristics.

The above specification, examples and data provide a description of themanufacture and use of the composition of the invention. Since manyembodiments of the invention can be made without departing from thespirit and scope of the invention, the invention also resides in theclaims hereinafter appended.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A method of forming a control module for anelectrical stimulation system, the control module comprising anelectronic subassembly disposed in an inner space of a casing and afeedthrough housing disposed along a portion of the casing, the methodcomprising: forming an RF-diverting assembly, the RF-diverting assemblycomprising a plurality of capacitive elements electrically coupled to afeedthrough ground; electrically coupling the plurality of capacitiveelements to a plurality of conductive pathways extending along anon-conductive substrate; electrically coupling the plurality ofconductive pathways to a plurality of feedthrough pins extending throughthe feedthrough housing from a location external to the casing to alocation within the inner space of the casing; electrically coupling theplurality of conductive pathways to the electronic subassembly such thatthe plurality of conductive pathways electrically couple the pluralityof feedthrough pins to the electronic subassembly; electrically couplingthe feedthrough ground to at least one electrically-conductive portionof the feedthrough housing; and electrically coupling the at least oneelectrically-conductive portion of the feedthrough housing to at leastone electrically-conductive portion of an outer surface of the casing.2. The method of claim 1, wherein electrically coupling the plurality ofcapacitive elements to a plurality of conductive pathways disposed alonga non-conductive substrate comprises electrically coupling the pluralityof capacitive elements to a plurality of conductive pathways via aplurality of conductive pads of the RF-diverting assembly.
 3. The methodof claim 2, wherein electrically coupling the plurality of capacitiveelements to a plurality of conductive pathways via a plurality ofconductive pads of the RF-diverting assembly comprises mechanicallycoupling each of the plurality of conductive pads directly to thenon-conductive substrate.
 4. The method of claim 2, wherein electricallycoupling the plurality of capacitive elements to a plurality ofconductive pathways via a plurality of conductive pads of theRF-diverting assembly comprises electrically coupling each of theplurality of conductive pads to a different one of the plurality ofconductive pathways extending along the non-conductive substrate.
 5. Themethod of claim 2, wherein electrically coupling the plurality ofcapacitive elements to a plurality of conductive pathways via aplurality of conductive pads of the RF-diverting assembly comprisesremovably attaching the plurality of conductive pads to thenon-conductive substrate.
 6. The method of claim 1, wherein thefeedthrough housing is formed from titanium.
 7. The method of claim 1,wherein electrically coupling the plurality of capacitive elements to aplurality of conductive pathways extending along a non-conductivesubstrate comprises electrically coupling the plurality of capacitiveelements to a plurality of conductive pathways extending along a flexcircuit.
 8. The method of claim 1, wherein electrically coupling thefeedthrough ground to at least one electrically-conductive portion ofthe feedthrough housing comprises electrically coupling the feedthroughground formed from at least one of nickel or nickel alloy to at leastone electrically-conductive portion of the feedthrough housing.
 9. Themethod of claim 1, wherein electrically coupling the feedthrough groundto at least one electrically-conductive portion of the feedthroughhousing comprises mechanically coupling the feedthrough ground directlyto the at least one electrically-conductive portion of the feedthroughhousing.
 10. The method of claim 1, wherein electrically coupling thefeedthrough ground to at least one electrically-conductive portion ofthe feedthrough housing comprises mechanically coupling the feedthroughground to the at least one electrically-conductive portion of thefeedthrough housing via one or more coupling pads disposed along thefeedthrough ground.
 11. The method of claim 1, wherein electricallycoupling the feedthrough ground to at least one electrically-conductiveportion of the feedthrough housing comprises at least one of welding orbrazing the feedthrough ground to the electrically conductive portion ofthe feedthrough housing.
 12. The method of claim 1, wherein electricallycoupling the feedthrough ground to at least one electrically-conductiveportion of the feedthrough housing comprises depositing the feedthroughground onto the electrically-conductive portion of the feedthroughhousing.
 13. The method of claim 1, further comprising mechanicallycoupling the feedthrough ground to the non-conductive substrate.
 14. Themethod of claim 13, wherein mechanically coupling the feedthrough groundto the non-conductive substrate comprises mechanically coupling thefeedthrough ground to the non-conductive substrate on an opposing majorsurface of the non-conductive substrate from each of the plurality ofcapacitive elements.
 15. The method of claim 13, wherein mechanicallycoupling the feedthrough ground to the non-conductive substratecomprises mechanically coupling the feedthrough ground to thenon-conductive substrate such that the non-conductive substrate issandwiched between the feedthrough ground and the feedthrough housing.16. The method of claim 1, further comprising disposing a connectorconfigured and arranged for receiving a lead or lead extension externalto the casing and in proximity to the feedthrough housing.
 17. Themethod of claim 16, wherein disposing a connector configured andarranged for receiving a lead or lead extension external to the casingand in proximity to the feedthrough housing comprises electricallycoupling the first ends of the plurality of feedthrough pins toconnector contacts disposed in the connector.
 18. The method of claim 1,further comprising electrically coupling each of a plurality ofinductors to a different one of the plurality of conductive pathways.19. The method of claim 1, further comprising coupling together adjacentcapacitive elements of the plurality of capacitive elements withadhesive.
 20. The method of claim 1, further comprising electricallycoupling the electronic subassembly to the at least oneelectrically-conductive portion of the casing via a ground line.